Spinal Cord Alpha Synuclein Deposition Associated with Spinal Myoclonus in a Patient with Multiple System Atrophy of the Cerebellar Type (MSA-C) (P4.310)
Bibliographic record
Abstract
Objective: To describe a clinical-pathological correlation between myoclonus and spinal cord alpha synuclein deposition in a patient with MSA-C. Background: MSA-C is a rare neurodegenerative disorder characterized by cerebellar ataxia and autonomic failure. Myoclonus in MSA-C is uncommon, its pathophysiology is poorly understood, and pathological findings have not previously been described. Methods: Case report. Results: A 66-year-old man of French Canadian ancestry presented with one year of dysarthria, gait ataxia, falls, impaired handwriting, dysphagia, and memory loss. He described erectile dysfunction for five years, symptoms of a REM sleep behavior disorder, urinary retention, constipation, and presyncope with standing. He was easily startled and had frequent asymmetric jerking movements of his extremities. Examination revealed a 10-point systolic blood pressure drop with standing, hypometric saccades, saccadic intrusions into pursuit eye movements, and mild dysarthria. Tone was decreased. Strength was full. He had dysmetria with finger-to-nose and heel-to-shin testing, and an ataxic gait, with a Brief Ataxia Rating Scale (BARS) score of 9/30. Multifocal startle myoclonus was prominent. Brain MRI showed cerebellar and pontine volume loss, and T2/FLAIR hyperintensities in the middle cerebellar peduncles. Extensive laboratory tests were negative, and a diagnosis of probable MSA-C was made. Spontaneous and startle multifocal myoclonus became overwhelming, with moderate response to levetiracetam. BARS score progressed to 25/30 five years after presentation. He died six years after symptom onset. Neuropathological examination revealed diffuse white matter loss in the cerebellum, basis pontis and middle cerebellar peduncles, and symmetric degeneration of the spinocerebellar and lateral corticospinal tracts. Microscopy identified abundant alpha synuclein deposition in oligodendroglia throughout the grey matter of the spinal cord, in both the anterior and posterior horns, and in descending more than ascending white matter tracts. Conclusions: This case appears to represent spinal myoclonus in MSA-C, caused by deposition of alpha synuclein in the spinal cord.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".